Intramolecularly Stabilized 1,4-Phenylene-Bridged Homo- and Heterodinuclear Palladium and Platinum Organometallic Complexes Containing N,C,N-Coordination Motifs; η1-SO2 Coordination and Formation of an Organometallic Arenium Ion Complex with Two Pt−C σ-Bonds

Abstract

The new ligand precursors [1-(Me3Si)-4-(R){C6(CH2NMe2)4-2,3,5,6}] (2, R = Me3Si; 3, R = H) have been used for the preparation of ionic 1,4-phenylene-bridged bispalladium(II) and palladium(II)-platinum(II) complexes [1-{M(MeCN)}-4-{M'(MeCN)}{C6(CH2NMe2)4-2,3,5,6}](BPh4)2 (5b, M = M' = Pd; 10, M = Pd, M' = Pt). Lithium-halogen exchange of the new ligand precursor C6Br2(CH2NMe2)4-2,3,5,6, 11, generates a presumably polymeric organodilithium reagent, 12, which in a transmetalation reaction with [PtCl2(Et2S)2] affords the 1,4-phenylene-bridged bisplatinum complex [1,4-(PtCl)2{C6(CH2NMe2)4-2,3,5,6}], 13. Reaction of colorless 13 with SO2 affords the unique orange bis-SO2 adduct [1,4-{PtCl(1-SO2)}2{C6(CH2NMe2)4-2,3,5,6}], 16, of which an X-ray crystal structure has been determined. The ionic derivative [1,4-{Pt(MeCN)}2{C6(CH2NMe2)4-2,3,5,6}](BPh4)2, 14b, obtained by reaction of 13 with AgOTf in MeCN followed by addition of NaBPh4, has been the subject of an X-ray crystal structure determination. The X-ray molecular structures of 5b, 10, and 14b have been determined and show intramolecular M···M distances of ca. 6.5 A. The bistriflate complex [1,4-{Pt(MeCN)}2{C6(CH2NMe2)4-2,3,5,6}](OTf)2, 14a, has also been used for the synthesis of the organometallic polymer {[1,4-{PtI(-I)}2{C6(CH2N(H)Me2)4-2,3,5,6}]n}(OTf)2n, 24. Triflate complex 14a slowly reacts with iodomethane to afford the dark red air-stable crystalline complex [1,4-{PtI}2{C6Me-1-(CH2NMe2)4-2,3,5,6}](OTf), 23. The X-ray molecular structure of 23 shows it to be a unique arenium ion species with two para-oriented -bonded iodoplatinum substituents.